Curtis lcd3215a Standby power only

[allsmith]

Re: Curtis lcd3215a Standby power only

Quote from retiredcaps''The main board uses the PS_ON pin to tell the rest of the power supply to start. If PS_ON is low, then the power supply will not start.'' end quote

I might be misunderstanding you,but the blue wire that is PS_ON, only has voltge (5v) on it when power button is turned on.
No voltage when power button is off.

The purple wire has 5v on it at all times.(would that mean that is the standby power for the main board?)

So if the main board is sending 5v through PS_ON to the power supply,wouldnt the 5v its getting be HIGH(on) and 0v be low (off)??

Or is it suppossed to be higher than 5v to trigger power supply??

Sorry if i'm misunderstanding you.

Also how do i Quote just part of somebodys post and get it to show up in blue like you are doing?? I cant figure it out!! Man! not only am i a noob at electronics and photography! im also a noob at forums!! lol sorry

[allsmith]

Re: Curtis lcd3215a Standby power only

You have at least 3 voltage regulators on your main board, possibly more, but the main board picture is obscured by wiring and the angle shot.

See my sig file on how to test a voltage regulator.

Note to selldoor. There are no regulators on the back although I do see a few diodes.

Thanks !! I tested 5, U designation regulators on main board,here are the results..

u18
78d051
ebvhab
pin 1 = 0.39v
pin 2 = 0.00v

u11
vc33c
r133al
pin 1 = 0.00v
pin 2 = 5.11v
pin 3 = 3.30v

u15
eh13a
828n90
pin 1 = 0.00v
pin 2 = 0.00v
pin 3 = 0.45v

u2
eh11a
839k32
pin 1 = 0.00v
pin 2 = 0.00v
pin 3 = 0.45v

u4
eh13a
828n90
pin 1 = 0.00v
pin 2 = 0.00v
pin 3 = 0.00v

[retiredcaps]

Re: Curtis lcd3215a Standby power only

You have at least 3 voltage regulators on your main board, possibly more, but the main board picture is obscured by wiring and the angle shot.

See my sig file on how to test a voltage regulator.

Note to selldoor. There are no regulators on the back although I do see a few diodes.

[retiredcaps]

Re: Curtis lcd3215a Standby power only

Steady green flashing led when power button is pushed
I tested for shorts on all large mosfets and bridge rectifier(none found)

Just some general hints for future troubleshooting.

When you get any sort of power LED light (red, green, flashing), that automatically tells you that the 5V standby is working. Since 5V standby is working, there is no need to test the bridge rectifier. If the bridge rectifier were bad, you wouldn't any DC voltage.

Should i pull the 4 rectifiers out of circuit to test??(I can post pic of how there in circuit if needed)

The main board uses the PS_ON pin to tell the rest of the power supply to start. If PS_ON is low, then the power supply will not start.

I dont know how to test the transformer.

The main transformer on the power rarely fails. In order to "properly" test it, you need a special tool called a ring tester. For example,

http://www.anatekcorp.com/bluert.htm

[allsmith]

Re: Curtis lcd3215a Standby power only

Here is a pic of the back of main board

[allsmith]

Re: Curtis lcd3215a Standby power only

can you check what voltage you get at each end of the 2 main board fuses
can you post pics of the back of the main board

0.00v on all ends when first plugged into wall.

0.40v on all ends when power button hit, but steadily drops to 0.05v on all pins within about 30 seconds.

Meter set to 20v scale

[selldoor]

Re: Curtis lcd3215a Standby power only

can you check what voltage you get at each end of the 2 main board fuses
can you post pics of the back of the main board

[allsmith]

Re: Curtis lcd3215a Standby power only

Please can you check if the 24V comes up without the inverter connected.

tested 1.5v at the pins where i disconnected the inverter wires

sorry gotta go to work,be back on here in about 8 hrs

Thanks i really appreciate it!!

[tom66]

Re: Curtis lcd3215a Standby power only

I left the inverter wires and green wires unpluged from power supply

Same test results as before
0.10v when pluged into wall
5.0v after hitting power button

Green led stayed solid on this time

Please can you check if the 24V comes up without the inverter connected.

[allsmith]

Re: Curtis lcd3215a Standby power only

Perhaps check the soldering on the transformer the pin just to the left of the third row down of 6 wide ventilation holes looks a bit off and this is in the hot (singed)area.

It seems to look ok to me.
Here is a close up pic
Thanks!!

[selldoor]

Re: Curtis lcd3215a Standby power only

Perhaps check the soldering on the transformer the pin just to the left of the third row down of 6 wide ventilation holes looks a bit off and this is in the hot (singed)area.

[allsmith]

Re: Curtis lcd3215a Standby power only

Another test - voltage across 450V cap should increase when you press the power button - should be around 400V when running, 165V when "off".

450v cap has 169v with tv off and just plugged in to wall.

379v when power button is pushed to on.

[allsmith]

Re: Curtis lcd3215a Standby power only

OK, so main board is probably okay, but voltages aren't coming up.

Can you try without the inverters and other 24V cables disconnected?

I left the inverter wires and green wires unpluged from power supply

Same test results as before
0.10v when pluged into wall
5.0v after hitting power button

Green led stayed solid on this time

[tom66]

Re: Curtis lcd3215a Standby power only

Another test - voltage across 450V cap should increase when you press the power button - should be around 400V when running, 165V when "off".

[tom66]

Re: Curtis lcd3215a Standby power only

OK, so main board is probably okay, but voltages aren't coming up.

Can you try without the inverters and other 24V cables disconnected?

[allsmith]

Re: Curtis lcd3215a Standby power only

Here are pics of the back of the power supply board

[allsmith]

Re: Curtis lcd3215a Standby power only

Does ON/OFF (blue wire) change when you press the power button?

Blue wire goes to 0.10v when tv is plugged in. DMM set on 20v

When power button is pushed voltage on blue wire goes to 5.0v

Stays at 5.0 even after hitting power button to turn off

Just seen a post of a you tube video that there is a thermal fuse in some transformers,could that be a possibility?

Not sure how to test transformers

Thanks!

[allsmith]

Re: Curtis lcd3215a Standby power only

Pity - they look ok Is there anything to see on the back of the singed area. Did you check that diode - use diode setting on meter and post results.

Diode test=
1/OL one direction
543 in other direction
DMM set to diode test

[tom66]

Re: Curtis lcd3215a Standby power only

Does ON/OFF (blue wire) change when you press the power button?

[selldoor]

Re: Curtis lcd3215a Standby power only

Pity - they look ok Is there anything to see on the back of the singed area. Did you check that diode - use diode setting on meter and post results.